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Layers of Earth's Atmosphere

The Earth's Atmosphere

The atmosphere surrounds Earth and protects us by blocking out dangerous rays
from the sun. The atmosphere is a mixture of gases that becomes thinner until
it gradually reaches space. The air in the atmosphere is essential to life
because it allows us to breathe.
Recently, there have been many studies on the atmosphere connected to the greenhouse
effect . The ozone layer has also been in the news a lot.

The atmosphere is divided into five layers depending on how temperature changes
with height. Most of the weather occurs in the first layer.

Layers of the Earth's Atmosphere

There are five layers
in the atmosphere. The atmosphere thins out until it reaches space.

The troposphere is where weather occurs. You breathe the air in the troposphere.

Many airplanes fly in the stratosphere because it is very stable. Also,
the ozone layer is there.

Many rock fragments from space burn up in the mesosphere.

The thermosphere is very thin. It's where the space shuttle orbits.

The upper limit of our atmosphere is the exosphere.

The Average Temperature Profile of Earth's Atmosphere

The Troposphere

The troposphere is the lowest layer of the Earth's atmosphere. The temperature
in the troposphere goes down as you go higher.

Weather occurs in the Earth's troposphere.

The Stratosphere

The stratosphere is the second layer of the atmosphere. The the temperature
in the stratosphere goes up the higher you go up.

Ozone causes the temperature to go up. It absorbs dangerous light from the
Sun and converts it to heat.

The stratosphere is located above the troposphere.

Ozone - An Overview

Have you ever heard of ozone? That's a word that shows up in the news a lot!
Do you know what ozone is and why it is important in the Earth's atmosphere?

Ozone
is made of three oxygen atoms (O3). You've probably heard of oxygen before
-- it's part of the air we breathe. The oxygen that we breathe is made up of
two oxygen atoms (O2). Add another oxygen atom, and you have ozone! When a
lot of ozone is around, you would see it as a pale blue gas. Ozone is found
in two different layers of the atmosphere, the stratosphere and the troposphere.
Where we find ozone in the atmosphere determines whether we consider it to
be "good" or "bad"!

In the troposphere, the ground-level or "bad" ozone is an air pollutant
that damages human health and plants. It is a key ingredient in smog. In the
stratosphere, we find the "good" ozone that protects life on Earth
from the harmful effects of the Sun. The simple saying "Good up high and
bad near by" sums up ozone in the atmosphere.

Ozone in the Stratosphere

Most of the ozone that we know about is found in the the stratosphere, the
second layer of the Earth's atmosphere. Ozone forms a kind of layer in the
stratosphere. This layer shields us from the Sun's ultraviolet light. This
ultraviolet light can cause damage to people like giving them skin cancer or
causing tissue damage to their eyes. Ultraviolet light can also be bad for
plants and animals.

The ozone layer would be very good at its job of protecting
Earth from too much ultraviolet radiation - that is, it would if humans did
not contribute
to things! Human-released chemicals are speeding up the breakdown of ozone,
so that there are "holes" now in our ozone protection shield.

Scientists know about this problem. They have told governments around the
world that they need to stop making and releasing these harmful chemicals that
break down ozone in the stratosphere. Countries have started doing this, and
scientists are hoping that this will eventually heal the "holes" that
were made in the ozone shield.

The Mesosphere

The mesosphere is the third layer in the atmosphere. The temperature drops
when you go higher, like it does in the troposphere. It can get down to -90°C
in the mesosphere. That's the coldest part of the atmosphere!

The mesosphere starts on top of the stratosphere. Sometimes you can see
the mesosphere by looking at the edge of a planet.

The Thermosphere

The thermosphere is the fourth layer of the Earth's atmosphere. It is found
above the mesosphere. The air is really thin that high up. The temperature
changes with the solar activity. If the sun is active, temperatures in the
thermosphere can get up to 1,500°C or higher!

The Earth's thermosphere also includes the region called the ionosphere.

The Ionosphere

The ionosphere is a special part of the atmosphere. It is not a separate layer,
but part of the thermosphere.

Different regions of the ionosphere make long distance radio communication
possible by reflecting the radio waves back to Earth. It is also home to auroras.

Temperatures in the ionosphere just keep getting hotter as you go up!

Regions of the Ionosphere

The ionosphere is broken down into the D, E and F regions.

The D region is
the lowest. Then comes the E region. The F region is the highest. You can
see this in the picture below.

This image shows how the ionosphere is divided even further into layers:
D, E, and F layers.

The Sun's Effect on the Ionosphere

The ionosphere is an invisible region found in the Earth's atmosphere. When
the Sun is more active, the ionosphere is thicker.

So things like flares and
coronal mass ejections will make the ionosphere thicker!

This image shows how different types of solar radiation (x-rays to infrared
radiation) penetrate into the Earth's atmosphere. It is this solar radiation
that ionizes the upper atmosphere, creating the ionosphere.

The Exosphere

The last layer of the Earth's atmosphere is the exosphere. This is the area
where atoms escape into space.

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